Machining a Pulley From Scrap #shorts

This #SHORTS project was meant to be a quick and dirty proof of concept, but once it got going it turned into several hours of fiddling. Don’t they always?

The material used for the pulley was an old die cast gearbox casing. It’s some sort of zinc alloy that is stiffer and harder than aluminium, but machines really nicely. I was just what I had to hand on the day.

I dialled in one of the existing features on the metal casing as there was barely enough material for what I had in mind. Possibly a bit overkill, close enough would probably have been good enough in this case. If you're interested in the tool I used, take a look here: https://youtu.be/WmjLUMajaPU

I took a preliminary pass and measured the resultant hole with a telescopic bore gauge.

A few people have pointed out the technique shown isn't great. The truth is there was a nice close up of me deftly rolling the gauge through the hole, but it was unusably out of focus, and it was too late to re-shoot by the time I realised, so I'm stuck with the wide shot. 🤷‍♂️

After adjusting the head I took another pass (actually it took two or three iterations to creep up on the dimension to avoid going over size) then switched to a drill chuck to add some holes.

I used coordinate drilling as the work was already clamped down and centred. The rotary table would just have added another complication. I spotted the positions with a centre drill then followed up with an 8mm bit.

After refitting the boring head I used a home made trepanning tool (ground from a broken end mill) to cut out the disk. A fret saw might have been quicker, but I needed the practice at this technique.

The 6800-2RS (10 x 19 x 5mm) bearing had its shields and factory grease removed (to be replaced with light oil). It will be very lightly loaded in a clean environment and I’m more interested in minimum drag rather than long life.

Before anyone chips in you can get those from such-a-place for pennies, you’re missing the point! Anyone can just buy something that somebody else has made. That teaches you nothing and isn’t nearly as much fun.

There’s an hour and three quarters of video shrunk down to make this 60 second short.

Manually subtitled for accuracy. Click on the CC box.
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Shot: HDC-HS700 1920x1080 50P AVCHD
Edit: DaVinci Resolve 18.1.4 ProRes 422
Mic: DR-05

Видео Machining a Pulley From Scrap #shorts канала The Recreational Machinist